Adaptive cruise control systems provide an adaptive vehicle speed control, based on sensing of another vehicle or target in front of the host vehicle within which the cruise control operates. Cruise control normally controls host vehicle speed to minimize a difference between actual vehicle speed and a driver-set speed. The adaptive speed control senses the presence of a vehicle or the like in front of the host vehicle and adjusts the cruise control algorithm to account for the target preceding the host vehicle, for example to reduce host vehicle speed and maintain a set distance between the vehicles. A number of different types of automobile manufacturers offer such adaptive cruise control as a comfort aid for driving.
Adaptive cruise control (ACC) systems typically utilize a radar or laser sensor or the like to detect the presence of and distance to a target vehicle leading the host vehicle on which the sensor and the ACC system are mounted. Adaptive cruise control sensors are now commonly mounted on motor vehicles, such as cars, trucks, lorries, vans and the like. Such an adaptive cruise control sensor is located to the front of the host vehicle, generally in the front bumper, and directs a radar beam forwardly in the direction of forward motion of the motor vehicle. Based on the return signal, whenever the sensor detects another vehicle in front of and in the path of the host vehicle, which is moving at a speed slower than the speed of the host vehicle, the adaptive cruise control system determines the speed of the leading vehicle from the sensor signal. The control of the adaptive system sets the cruise speed of the host vehicle to the speed of the leading vehicle.
In order for such an adaptive cruise control system to operate properly, the sensor must be aligned with the vehicle thrust line, and implementation of such a system requires accurate alignment of the sensor with that thrust line. It is essential that the sensor axis, and thus the axis along which the sensor emits a radar or laser beam, extends parallel to the thrust line of the vehicle. In certain cases, the axis of the adaptive cruise control sensor may coincide with the thrust line, although in general, the axis of the adaptive cruise control sensor tends to be spaced apart from the thrust line, but must be parallel thereto.
The thrust line of a vehicle is determined by the toe of the rear wheels of the vehicle, and techniques for measurement thereof will be well known to those skilled in the art. It is a line that extends from the point of intersection of the rear transverse axis of the rear wheels and the longitudinal center line of the vehicle, and it extends forwardly of the vehicle at an angle to the center line of the vehicle. The angle that the thrust line makes with respect to the center line of the vehicle is determined by the toe of the rear wheels, and is relatively small.
Devices for aligning the axis of an adaptive cruise control sensor are known. In general, such a device comprises a mirror and a laser beam. An arrangement is provided for mounting the mirror or the laser light beam source forwardly of the vehicle for cooperating, with the other of the source and the mirror, which is mounted on the adaptive cruise control sensor. Typically, the laser light beam source is mounted on the adaptive cruise control sensor, and the source is arranged with its axis, and in turn, the axis at which the light beam is projected, extending parallel to and relatively close to the axis of the adaptive cruise control sensor. In this arrangement, the mirror is mounted on a separate stand or the like in front of the vehicle.
German published patent application DE 19857871 (C1) discloses a device for aligning the sensor of an adaptive cruise control system to the thrust line of the host vehicle. The disclosed device uses a laser source mounted on a frame positioned in front of the automobile, for directing a laser beam onto a mirror provided by the radar sensor perpendicular to the propagation direction of the radar beam. The rear wheels of the automobile have angle sources, which are used for alignment of the frame with the automobile longitudinal axis in conjunction with angle sources at the opposite sides of the frame, with correction of the radar sensor using evaluation of the reflected laser beam.
Where the mirror is the separately mounted element, it is essential that the mirror is aligned with the vehicle such that the mirror extends transversely across the vehicle thrust line, that is to say perpendicular to the thrust line. In general, it is difficult to locate the mirror so that it accurately extends perpendicular to the thrust line. In cases where the mirror is mounted on the adaptive cruise control sensor, the mirror is mounted transversely of the vehicle thrust line, and the laser light beam source is separately mounted. In this later case, the laser light beam source must be located with the axis of the light beam source extending parallel to the thrust line. It is often difficult to accurately align the laser light beam source on a mounting with the beam source axis extending parallel to the thrust line.
It is well known to align the front and rear wheels of a vehicle with alignment devices or systems. Modern wheel alignment systems, providing increased accuracy and ease of use, have relied on visible targets and computer processing of camera images of the wheel mounted visible targets. Such systems are often referred to as 3D image wheel aligner systems. Examples of methods and apparatus involving computerized image processing for alignment of motor vehicles are described in U.S. Pat. No. 5,943,783 entitled “Method and apparatus for determining the alignment of motor vehicle wheels;” U.S. Pat. No. 5,809,658 entitled “Method and apparatus for calibrating cameras used in the alignment of motor vehicle wheels;” U.S. Pat. No. 5,724,743 entitled “Method and apparatus for determining the alignment of motor vehicle wheels;” and U.S. Pat. No. 5,535,522 entitled “Method and apparatus for determining the alignment of motor vehicle wheels.” A wheel alignment system of the type described in these references is sometimes called a “3D aligner” or “visual aligner.” An example of a commercial vehicle wheel aligner is the Visualiner 3D, commercially available from John Bean Company, Conway, Ark., a unit of Snap-on Tools Company.
The prior adaptive cruise control sensor alignment devices, including that disclosed in DE 19857871 (C1), have been designed for use with older alignment measurement heads. In view of the increased accuracy and ease of use, it would be advantageous if the 3D type visual aligner systems could be used to also perform alignment of an adaptive cruise control sensor. The prior adaptive cruise control sensor alignment devices, however, do not work with the more modern 3D type visual aligner systems, due to limiting parameters of the 3D visual aligner and/or the sensor itself.
Hence a need exists for an apparatus for use with a visual aligner system, such as used for wheel alignments, to allow the aligner to also perform an alignment of the sensor of the adaptive cruise control system on a host vehicle. There is an attendant need for a method that facilitates the alignment of an adaptive cruise control sensor of a vehicle using a 3D image wheel aligner.